Hydraulic cylinder modular structure

ABSTRACT

A modular structure for a hydraulic cylinder permitting the cylinder to be used in combination with a reservoir of hydraulic fluid either installed on the cylinder itself or at a remote location with a conduit connection to the cylinder. The cylinder is provided with a peripherally threaded portion over which a tubular member formed integral with the reservoir, or in the alternative, provided with a connector for connection of the cylinder to a remotely located reservoir is fitted. The tubular member-fluid reservoir assembly and the tubular member-connector assembly are interchangeable.

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for transmitting mechanicalmovement from one location to another, and which utilizes hydraulicfluid as a transmitting means. More particularly the invention pertainsto a force transmission device employing hydraulic cylinders andinterconnecting the cylinders, whereby pressure generated in onecylinder is transmitted to the other to achieve a desired movement oroperation at a location remote from that at which the pressure forceoriginates.

Such devices may be used for effecting mechanical operations in motorvehicles. For example, hydraulic cylinders are used in actuatingmechanical clutches. In such use, a "master" cylinder is utilized tooriginate pressure-flow which is transmitted by a conduit to a "slave"cylinder having an output member connected to the clutch releasemechanism. The master cylinder is usually operated by means of a footpedal.

It is common practice to mount the master cylinder on a bulkhead orother structure forming part of a cab, or other driver enclosure, whilethe slave cylinder is mounted on the clutch housing or the gear boxhousing of the vehicle. It is known to supply one of the cylinders withhydraulic fluid from a reservoir which provides a continuous means ofreplenishing the hydraulic fluid system, the object being to insurecontinued proper operation.

It is also known to provide a remotely positioned, i.e. separatehydraulic fluid reservoir, connected by a conduit to a cylinder, as wellas a reservoir that is integral with a cylinder and has more directfluid connection with the cylinder such as by means of openingsextending through contacting walls.

In some instances, one arrangement is desirable, whereas in otherinstances the other is preferred. Usually the reservoir is connected tothe master cylinder. Master cylinders known in the art are either of onedesign having a reservoir integral therewith or of another distinctdesign, so far as structure is concerned, suited for connection to aremotely located reservoir. In effect two distinct master cylinders andtwo distinct reservoirs must be made by suppliers to accommodate therequirements of their vehicle manufacturing customers.

DESCRIPTION OF THE PRIOR ART

U.S. Pat. No. 4,407,125 discloses a clutch actuating hydraulic systememploying a master cylinder, adapted to be mounted on a vehiclebulkhead, and a slave cylinder, the cylinders being interconnected by aconduit, and wherein the master cylinder has a hydraulic fluid reservoirintegral therwith. Hydraulic fluid thus can be replenished as neededdirectly from the reservoir to the master cylinder without interveningtubing.

SUMMARY OF THE INVENTION

The instant invention provides a single master cylinder structure usefulboth for installations where a unitary cylinder-reservoir assembly ispossible and desirable, as well as for installations where a remotelylocated reservoir, with respect to the cylinder, is necessary orotherwise desired.

According to the invention, a cylinder and reservoir construction isprovided which can be either securely joined to each other to form asingle cylinder-reservoir unit or which can be positioned separate fromeach other and connected by a conduit without structural modification ofeither.

Further, according to the invention, simplicity of structure is achievedas well as secure reliable means of joining the cylinders and reservoirsto each other.

The concept includes provision of a cylinder having an exteriorconfiguration that matches a reservoir having a mating configurationsuch that they can be readily interlocked to provide a single unit, orwhich can be separately used. According to the invention there is alsoprovided a third element of simple design that can be readily securelyattached to the same cylinder in place of a reservoir to serve as aconnector for joining the cylinder to a reservoir in installations wherethe two are remotely located from each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevation of an example of master and slavecylinder assembly for operating a motor vehicle mechanical clutch, andshowing a form of cylinder-reservoir assembly according to theinvention;

FIG. 2 is a longitudinal sectional view of the cylinder-reservoirassembly of FIG. 1;

FIG. 3 is a longitudinal sectional view of the reservoir portionthereof;

FIGS. 4 and 5 are fragmentary sections taken respectively along lines4--4 and 5--5 of FIG. 2;

FIG. 6 is a view similar to FIG. 1, but illustrating a modificationwherein the master cylinder is provided with a remotely locatedreservoir;

FIG. 7 is a longitudinal sectional view of the cylinder of FIG. 6;

FIG. 8 is a longitudinal section through the hydraulic fluid conduitconnector portion of FIG. 7;

FIG. 9 is a side elevation of a modular hydraulic cylinder according tothe present invention; and

FIG. 10 is a view similar to FIG. 9 and illustrating a modificationthereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, a cylinder-reservoir combination is illustratedas comprising a hydraulic cylinder 10 and a hydraulic fluid reservoir 12forming a single assembly 14. The cylinder 10 has a cylindrical exteriorsurface 16 along at least a portion of its length as shown at 16, FIGS.2 and 9. The reservoir 12 has a mating integral tubular portion 18. Thecylindrical surface portion 16 of the cylinder terminates in a shoulderabutment 20 at one end, defined on the side face of a flange 21, whilethe tubular portion 18 of the reservoir 12 has a terminal abuttingannular face 22 at one corresponding end, FIG. 2. The other end of thereservoir tubular portion 18 is provided with an internally threadedsection 24. The cylinder 12 has a mating peripherally threaded section26. The maximum diameter of the cylinder threaded section 26 is slightlyless than the diameter of the cylinder cylindrical surface 16 and,correspondingly, the minor diameter of the internally threaded portion24 of the tubular member 18 is less than the diameter of the bore 36 ofthe reservoir tubular member 18. In this manner, the reservoir tubularportion 18 may be slipped over the cylinder cylindrical peripheralsurface 16 and the respective threaded portions 24 and 26 engaged byrotating the reservoir 12 relative to the cylinder 10 until the annularabutment 22 of the reservoir tubular member 18 engages the surface ofthe cylinder shoulder abutment 20.

The hydraulic fluid reservoir 12 per se may generally be according tothe structure disclosed in U.S. Pat. No. 4,407,125 or, preferably, incopending application Ser. No. 599,248, now U.S. Pat. No. 4,506,507,issued Mar. 26, 1985, both assigned to the same assignee as the presentapplication. The reservoir 12 comprises a hydraulic fluid chamber 40separated from the ambient by a flexible cup-shaped diaphragm member 42.The diaphragm member 42 has a lip 44 adapted to seat on the flange 46 ofthe reservoir open top 48 and be secured thereto by a closure cap 50,all in a known manner. The flexible diaphragm 42 is exposed toatmospheric pressure through a vent port, not shown, in the closure cap50. The flexible diaphragm 42 is preferably formed of a flexibleimpervious material such as neoprene.

The reservoir 12 is also provided with a mounting means such as amounting flange 51, for the purpose of mounting on a bulkhead or thelike. The mounting means may also take the form of a quick connect.twist and lock, structure as disclosed in co-pending application Ser.No. 387,019, filed June 10, 1982 now U.S. Pat. No. 4,488,701, issuedDec. 18, 1984, assigned to the same assignee as the present application.

The cylinder 12 has a bore 52 in which is reciprocably disposed a piston53 having a spool 54 and seals such as 56 and 58. A compression coilspring 60, disposed between the end of the bore 52 and an extension ofthe spool 54, urges the piston 53 to the right as viewed in FIG. 2. Thepiston 53 is controllably displaceable by a rod 62, having an endconnected to a foot pedal 64, for transferring hydraulic fluid from thecylinder 12 to a remotely located slave cylinder 66 through a flexibleconduit 68 for operating, for example, a motor vehicle clutch releasemechanism, not shown, by means of the slave cylinder output member 74.

As seen in FIGS. 2, 3 and 4, the hydraulic fluid reservoir 12 has anorifice 84 extending through its bottom wall 86. The cylinder 12 has arelatively wide peripheral groove 87 forming an annular chamber 88 cutinto its exterior surface. The locations of the orifice 84 and of thechamber 88 are such that when the reservoir 12 is securely fastened ontothe cylinder 12 as illustrated at FIG. 2 the orifice 84 and the chamber88 are in fluid communication. A port 90 places the chamber formed inthe cylinder bore 52 forward of the piston 53 in fluid communicationwith the annular space 88 and with the fluid chamber 40 of the reservoir12 through the orifice 84 on the bottom of the fluid reservoir 12, suchas to maintain the hydraulic apparatus constantly filled with fluid. Assoon as the piston 53 is reciprocated such as to displace hydraulicfluid from the master cylinder 10 to the slave cylinder 66 through theconduit 68, the orifice or port 90 is obturated by the seal 56 and spool54. A second orifice or port 92 disposed behind the spool 54, alsoplaces the annular space 88 in fluid communication with an annularchamber 94 formed in the cylinder bore 52 behind the piston spool 54,such that the chamber 94 is always filled with hydraulic fluid, as iswell known in the art. A pair of O-rings 96, disposed in appropriateperipheral grooves 98 on both sides of the groove 87 forming the annularspace 88, provide a leak-proof connection between the cylinder 10 andthe reservoir 12.

FIG. 6 illustrates generally a master cylinder 10 provided with aremotely installed hydraulic fluid reservoir 12' connected to the mastercylinder 10 via a flexible conduit 100. The master cylinder 10 isprovided with a modular sleeve 102 having an appropriate fitting 104 towhich is connected the end of the conduit 100. The sleeve 102, FIG. 8,is an exact replacement for hydraulic fluid reservoir 12 of FIGS. 1-5,being provided internally with a smooth bore portion 36 having aninternally threaded end portion 24 for engagement with the peripherallythreaded portion 26 of the master cylinder 10, FIG. 7.

FIG. 8 illustrates the details of the sleeve 102, which is shown at FIG.7 installed over the cylinder 10, and a comparison between FIGS. 2 and 7immediately reveals that the structures of the cylinders 10 areidentical.

As illustrated at FIG. 10, the annular abutment surface 20 engaged bythe annular end face 22 of the connector annular sleeve 102 may,alternatively, take the form of a spring split ring 106 installed in anappropriate groove 108 formed in the peripheral surface of the cylinder10. The side face of the split ring 106 thus defines the annularabutment 20 for the end face 22 of the connector sleeve 102 of FIG. 8 aswell as of a tubular section 18 of the reservoir 12 of FIG. 3.

Having thus described in the present invention by way of examples ofstructure thereof, modifications whereof will be apparent to thoseskilled in the art.

What is claimed as new is as follows:
 1. A hydraulic cylinder assemblyfor a hydraulic apparatus, said hydraulic cylinder assembly consistingof a hydraulic cylinder having a circularly cylindrical housing and aseparate detachable and interchangeable tubular member open at both endsand fitted over said cylindrical housing, said cylindrical housingcomprising a peripherally recessed portion defining a first annulargroove, a peripherally threaded portion disposed on one side of saidfirst groove, an outwardly extending annular abutment shoulder on theother side of said first groove, a first annular seal disposed in asecond peripheral groove between said one side of said first groove andsaid peripherally threaded portion, a second annular seal disposed in athird peripheral groove between said other side of said first groove andsaid annular abutment shoulder, and at least one portion through thewall of said cylindrical housing leading in said first groove, and saiddetachable and interchangeable tubular member having a bore comprising asmooth portion engaged with said first and second annular seals, aninternally threaded portion mating said externally threaded portion ofsaid cylindrical housing and an end defining an annular face engagedwith said abutment shoulder of said cylindrical housing when saidtubular member is threaded over said cylindrical housing, said tubularmember having an orifice in its bore for supplying fluid to said firstgroove and to the interior of said cylinder housing through said portthrough the wall of said cylindrical housing.
 2. The hydraulic cylinderof claim 1 wherein said tubular member is formed integral with areservoir of hydraulic fluid.
 3. The hydraulic cylinder of claim 1wherein said tubular member has a fitting for connection of said orificewith a remotely located reservoir of hydraulic fluid through a conduit.4. The hydraulic cylinder of claim 1 wherein said tubular member has anintegral mounting flange for mounting said cylinder on a support.
 5. Thehydraulic cylinder of claim 2 wherein said tubular member has anintegral mounting flange for mounting said cylinder on a support.
 6. Thehydraulic cylinder of claim 3 wherein said tubular member has anintegral mounting flange for mounting said cylinder on a support. .Iadd.7. A hydraulic cylinder assembly for a hydraulic apparatus, saidhydraulic cylinder assembly comprising:A) a hydraulic cylinder includinga circularly cylindrical hollow housing member open at one end thereofand closed at the other end thereof and defining a central bore and anannular external shoulder spaced axially from and facing said openingend thereof; B) a piston slidably disposed in said bore; C) a piston rodextending through said open end of said housing member for connectionwithin said bore to said piston; D) a separate detachable andinterchangeable tubular member including a tubular sidewall open at bothends, fitted over said open end of said cylindrical housing member, anddefining an annular abutment surface at one end thereof for abuttingcoaction with said annular shoulder; E) an annular groove defined at theinterface of said members between said shoulder and said open end ofsaid housing member; F) a radial reservoir port in said sidewall of saidtubular member communicating at its radially inner end with said grooveand adapted to communicate at its radially outer end with a reservoirfor said hydraulic apparatus; G) a radial throughport in the wall ofsaid housing member communicating with said groove; H) means defining afirst annular seal at the interface of said members between said grooveand said open end of said housing member; I) means defining a secondannular seal at the interface of said members between said groove andsaid shoulder; and J) means maintaining said tubular member in fixedaxial and angular relation on said housing member with said abutmentsurface abuttingly engaging said shoulder. .Iaddend. .Iadd.
 8. Thehydraulic cylinder assembly of claim 7 wherein said assembly furtherincludes:K) a flange extending radially outwardly from said tubularmember between said reservoir port and said open end of said housingmember for mounting said cylinder assembly to a support structure..Iaddend.